STEAMBOAT SPRINGS — Routt County Sheriff’s Office deputies were going door-to-door Monday afternoon to let about 30 households in West Routt County know they should start preparing to flee a rapidly growing wildfire.

The Deep Creek Fire, initially dubbed the Steer Park Fire, grew from 2 acres to 419 acres in only a few hours Monday near the Wolf Mountain Ranch between Milner and Hayden.

The blaze — which officials said might have resulted from a reignition of a wildfire started last week by a suspected lightning strike — was discovered about noon.

Deputies gave pre-evacuation notices to residents who were within a 5-mile radius of the fire along Routt County Road 52.

At 6 p.m. the fire was burning less than a mile from structures at Wolf Mountain Ranch.

A heavy air tanker dropped retardant on a ridge a few miles from the ranch as firefighters worked to guard nearby structures.

Smaller planes and a helicopter also made passes, planning the aerial attacks and mapping the course of the blaze.

“It looks like it’s calmed down a bit,” Routt County Emergency Management Director David “Mo” DeMorat said with a slight sense of relief just before sunset. Earlier in the day, firefighters had staged closer to the fire. But a helicopter flying above warned crews on the ground the flames were moving in their direction, so they pulled back.

DeMorat pointed to a stand of trees that were on fire about three quarters of a mile from the command post and noted that was the location the firefighters had staged earlier.

“This thing grew really fast on us,” he said.

He said a combination of wind, terrain and dry conditions fueled the flames and sent the fire southeast, toward Wolf Mountain Ranch.

Firefighters from Hayden, Steamboat Springs and Oak Creek were all on scene by Monday afternoon.

A helicopter and other resources that were fighting the Big Red Fire in North Routt County also were called to help attack the new blaze.

DeMorat said the fire is burning in the same location as the Steer Park Fire, which was discovered about a week earlier.

Officials are investigating whether the fire that blew up Monday was a reignition of that fire, which is believed to have been caused by a lightning strike.

DeMorat urged Routt County residents who haven’t signed up for the new Everbridge emergency notification system to do so in the wake of the fire.

He said when the alert went out, only one residence within a 5-mile radius of the blaze was signed up and received the notification about the pre-evacuation.

DeMorat said it was likely about 30 residences in the area needed to receive the notification.

“It’s so critical when you get to this part of the county,” he said, noting how far apart residences were.

Residents can register with Everbridge by visiting routtcountyalerts.com.

The large plume of smoke the fire put up in the afternoon was visible from downtown Steamboat.

Monday was the second time this summer that local firefighters have had their holidays interrupted by wildfires.

Several firefighters had to spend the Fourth of July holiday battling the Mill Creek Fire near California Park.